1. Field of the Invention
This invention relates in general to a moveable transducer head assembly for displacing a magnetic head relative to traces recorded on magnetic tape and in particular to an improved transducer head which moves the head substantially in a linear direction rather than in an arc.
2. Description of the Prior Art
It is known to use automatic head tracking systems in video recorders wherein the head is deflected in a controlled manner so that the magnetic head will scan a video tape so as to maintain alignment with the magnetic tracks on the tape at different tape speeds or even when the tape is stopped. Particularly during the so-called special reproduction modes, such as slow, fast, reverse and stop modes it is necessary to move the head relative to the tape to maintain alignment. It has been known in the prior art to use bi-morph leaves which are made of piezoelectric ceramic material to support the head. However, deflection of the bi-morph leaf moves the head not parallel to the surface of the tape but in an arc which destroys the alignment of the head with the tape and also results in substantial reduction in the quality of the reproduced signal.
Disadvantages of the bi-morph supported head is that the bi-morph is subjected to hysteresis loss in response to the driving voltage so when the driving voltage returns to zero the magnetic head does not return to the zero reference position. Furthermore, the head assembly cannot be moved very large distances which are required particularly at high speed modes.
U.S. Pat. No. 4,151,569 discloses in FIG. 10 a head carrying plate which can be controlled with electromagnets so as to cause tracking of the magnetic head. This apparatus however causes the head supporting plate to move in an arc and thus is subject to the disadvantages of prior art bi-morph heads.